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Abstract:

A track link has a link body. The link body of the track link may include
a first substantially planar side surface, a second substantially planar
side surface opposite the first substantially planar side surface, a shoe
face extending between the first and second substantially planar side
surfaces, and a roller rail extending between the first and second
substantially planar side surfaces opposite the shoe face.

Claims:

1. A track link, comprising: a link body, including a first substantially
planar side surface, a second substantially planar side surface opposite
the first substantially planar side surface, a shoe face extending
between the first and second substantially planar side surfaces, and a
roller rail extending between the first and second substantially planar
side surfaces opposite the shoe face.

2. The track link of claim 1, wherein the link body further comprises: a
first opening extending from the first substantially planar side surface
to the second substantially planar side surface; a second opening
extending from the first substantially planar side surface to the second
substantially planar side surface; and wherein the first and second
openings are the only openings that extend from the first substantially
planar side surface to the second substantially planar side surface.

3. The track link of claim 2, wherein the first substantially planar side
surface and the second substantially planar side surface are
substantially parallel to one another.

4. The track link of claim 1, wherein the first substantially planar side
surface and the second substantially planar side surface are
substantially parallel to one another.

5. The track link of claim 1, wherein the link body further comprises a
mounting hole extending from the shoe face into the link body toward the
roller rail.

6. The track link of claim 5, wherein the mounting hole includes a
threaded portion.

7. The track link of claim 6, wherein the mounting hole includes an
unthreaded counterbore between the threaded portion and the shoe face.

8. The track link of claim 7, wherein the unthreaded counterbore has a
length of at least about 1/2 of a diameter of the unthreaded counterbore.

9. The track link of claim 7, wherein the unthreaded counterbore has a
length of at least about 3/4 of a diameter of the unthreaded counterbore.

10. The track link of claim 6, wherein the link body has a width between
the first substantially planar side surface and the second substantially
planar side surface, the width of the link body being at least about 11/4
times a diameter of the threaded portion of the mounting hole.

11. A track link, comprising: a link body without a nut seat, the link
body including; a first side surface, a second side surface opposite the
first side surface, a shoe face extending between the first and second
side surfaces, and a roller rail extending between the first and second
side surfaces opposite the shoe face.

12. The track link of claim 11, wherein the link body further comprises a
mounting hole extending from the shoe face into the link body toward the
roller rail.

13. The track link of claim 12, wherein the mounting hole includes a
threaded portion.

14. The track link of claim 13, wherein the mounting hole includes an
unthreaded counterbore between the threaded portion and the shoe face.

15. The track link of claim 14, wherein the unthreaded counterbore has a
length of at least about 1/2 of a diameter of the unthreaded counterbore.

16. The track link of claim 14, wherein the unthreaded counter bore has a
length of at least about 3/4 of a diameter of the unthreaded counterbore.

17. The track link of claim 13, wherein the link body has a width between
the first substantially planar side surface and the second substantially
planar side surface, the width of the link body being at least about 11/4
times a diameter of the threaded portion of the mounting hole.

18. The track link of claim 11, wherein: the first side surface is
substantially planar; and the second side surface is substantially
planar.

19. A track link, comprising: first side surface; a second side surface
opposite the first side surface; a shoe face extending between the first
and second side surfaces; a roller rail extending between the first and
second side surfaces opposite the shoe face; and an opening extending
across a width of the track link from the first side surface to the
second side surface, the opening including a pin bore, and a counterbore
having a larger cross-section than the pin bore, the counterbore having a
length of less than about 1/3 of a length of the pin bore.

20. The track link of claim 19, wherein: the first side surface is
substantially planar; the second side surface is substantially planar and
substantially parallel to the first side surface.

21. A track link, comprising: a shoe face; a roller rail opposite the
shoe face; a first end; a second end; a first side surface extending from
the first end to the second end between the shoe face and the roller
rail, the first side surface being free of projections; and a second side
surface extending from the first end to the second end between the shoe
face and the roller rail opposite the first side surface, the second side
surface being free of projections.

22. The track link of claim 21, wherein the first side surface extends
substantially parallel to the second side surface.

23. The track link of claim 22, wherein: a portion of the first side
surface adjacent the first end is laterally offset relative to a portion
of the first side surface adjacent the second end; and a portion of the
second side surface adjacent the second end is laterally offset relative
to a portion of the second side surface adjacent the first end.

24. The track link of claim 23, further comprising: a first opening
extending from the first side surface to the second side surface adjacent
the first end; and a second opening extending from the first side surface
to the second side surface adjacent the second end.

25. The track link of claim 24, wherein the first opening includes: a pin
bore, and a counterbore having a larger cross-section than the pin bore.

26. The track link of claim 25, wherein the counterbore has a length of
less than about 1/3 of a length of the pin bore.

27. The track link of claim 26, further comprising: a third opening
extending from the first side surface to the second side surface between
the first opening and the second opening, a portion of the third opening
proximate the shoe face defining a first nut seat; a fourth opening
extending from the first side surface to the second side surface between
the first opening and the second opening, a portion of the fourth opening
proximate the shoe face defining a second nut seat; a first mounting hole
extending from the shoe face to the first nut seat; and a second mounting
hole extending from the shoe face to the second nut seat.

28. The track link of claim 24, further comprising: a third opening
extending from the first side surface to the second side surface between
the first opening and the second opening, a portion of the third opening
proximate the shoe face defining a first nut seat; a fourth opening
extending from the first side surface to the second side surface between
the first opening and the second opening, a portion of the fourth opening
proximate the shoe face defining a second nut seat; a first mounting hole
extending from the shoe face to the first nut seat; and a second mounting
hole extending from the shoe face to the second nut seat.

29. An undercarriage assembly, comprising: a track link having a first
mounting hole with a threaded portion, a track shoe having a second
mounting hole aligned with the first mounting hole; and a bolt extending
through the second mounting hole into the threaded portion of the first
mounting hole, the bolt securing the track shoe to the track link.

30. The assembly of claim 29, wherein the first mounting hole includes an
unthreaded counterbore between the threaded portion and the second
mounting hole.

31. The assembly of claim 30, wherein the unthreaded counterbore has a
length of at least about 1/2 of a diameter of the unthreaded counterbore.

32. The assembly of claim 31, wherein a portion of the track link
containing the first mounting hole has a width of at least about 11/4
times a diameter of the threaded portion of the first mounting hole.

33. The assembly of claim 30, wherein the unthreaded counterbore has a
length of at least about 3/4 of a diameter of the unthreaded counterbore.

34. The assembly of claim 33, wherein a portion of the track link
containing the first mounting hole has a width of at least about 11/4
times a diameter of the threaded portion of the first mounting hole.

35. The assembly of claim 29, wherein a portion of the track link
containing the first mounting hole has a width of at least about 11/4
times a diameter of the threaded portion of the first mounting hole.

Description:

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Patent
Application No. 61/666,567, filed Jun. 29, 2012, which is hereby
incorporated by reference in its entirety.

[0003] Many mobile machines have tracked undercarriages that move along
the ground as the machine travels. For example, many earthmoving machines
like tractors and excavators may have such undercarriages. In known
undercarriage designs, many of the parts have complex geometric designs
that drive considerable manufacturing costs. FIGS. 1A-1C provide examples
of certain undercarriage components and their complex designs.

[0004] FIG. 1A shows a portion of a prior art link assembly 400, which
serves as the flexible backbone of the endless track of an undercarriage.
Link assembly 400 includes a plurality of links 401 assembled into
laterally spaced pairs connected to one another at pivot joints 403. Each
link 401 includes sides 402. Additionally, each of links 401 includes a
roller rail 405 on which rollers (not shown) of the undercarriage ride
during operation. Collectively, the roller rails 405 of links 401 form
two roller rails 407 of the link assembly 400.

[0005] As FIG. 1A shows, links 401 have complex shapes. The sides 402 of
links 401 have complex contours with curves, recesses, and projections.
Additionally, the roller rail 405 of each link has a wide portion in the
middle and laterally offset narrower portions on its ends. At each pivot
joint 403, laterally offset narrow portions of the roller rails 405 of
two connected links 401 sit beside one another and collectively provide a
bearing surface of substantially the same width as that provided by the
center portion of the roller rail 405 of each link 401. This gives each
overall roller rail 407 of the link assembly 400 a substantially constant
width. This also ensures that each of roller rails 407 presents a
substantially continuous straight outer guide surface 412 with which
outer guide flanges of the rollers can remain substantially continuously
engaged.

[0006] Opposite roller rails 405, links 401 include provisions for
attaching track shoes (not shown) to the links. Each link includes
windows 406 in its sides 402. Below each window 406, each link 401
includes a hole 409 for receiving a bolt, as well as a nut seat 408 for
receiving a nut to secure the bolt. To secure a track shoe to each link
401, the track shoe may be placed against the side of the link below the
holes 409, bolts may be inserted through holes in the track shoe and the
holes 409, and a nut may be secured on the bolt against nut seat 408.

[0007] FIGS. 1B and 1C, show a prior art idler 414 for an undercarriage.
Similar to links 401, idler 414 has a complex design. FIG. 1B provides a
perspective view of the idler 414, and FIG. 1C provides a cross-section
through a rotational axis of the idler 414. Idler 414 includes a hub 416
and a body 418. Hub 416 is constructed of two pieces welded together in
the middle. Body 418 is hollow with a cavity 420 inside it. Body 418
includes side plates 422 and a rim 424. Side plates 422 are frustoconical
discs that are welded to hub 416. Side plates 422 extend away from one
another as they extend radially outward from hub 416. Rim 424 may be a
ring that extends around radially outer portions of webs 422. Rim 424 may
be welded to the radially outer portions of webs 422. Rim 424 may include
a center flange 426 flanked by a pair of tread shoulders 428. Tread
shoulders 428 may be disposed radially inward of the outer surface of
center flange 426. In operation, center flange 426 may sit between links
401, and tread shoulders 428 may ride on the roller rails 407 of link
assembly 400.

[0008] Geometrically complex designs like those shown in FIGS. 1A-1C may
provide certain benefits that are particularly important for some
applications. However, these complicated designs also have certain
drawbacks. For example, manufacturing components like those shown in
FIGS. 1A-1C may prove undesirably expensive. Manufacturing links 401 with
their offset roller rails 405 and other complex geometric features may
involve expensive processes, such as forging or casting. Manufacturing
the complex shapes of the webs 422 and rim 424 of idler 414 also involve
expensive processes like forging or other forming processes. All of these
expensive manufacturing processes may undesirably increase the cost of
the undercarriage. The disclosed embodiments may help solve these issues.

SUMMARY

[0009] One disclosed embodiment relates to a track link. The track link
may have a link body. The link body of the track link may include a first
substantially planar side surface, a second substantially planar side
surface opposite the first substantially planar sides surface, a shoe
face extending between the first and second substantially planar side
surfaces, and a roller rail extending between the first and second
substantially planar side surfaces opposite the shoe face.

[0010] Another disclosed embodiment relates to a track link. The track
link may, include a link body without a nut seat. The link body may
include a first side surface, a second side surface opposite the first
side surface, a shoe face extending between the first and second side
surfaces, and a roller rail extending between the first and second side
surfaces opposite the shoe face.

[0011] A further disclosed embodiment relates to a track link. The track
link may include a first side surface, a second side surface opposite the
first side surface, a shoe face extending between the first and second
side surfaces, and a roller rail extending between the first and second
side surfaces opposite the shoe face. The track link may also include an
opening extending across a width of the track link from the first side
surface to the second side surface. The opening may include a pin bore
and a counterbore having a larger cross-section than the pin bore, the
counterbore having a length of less than about 1/3 of a length of the pin
bore.

[0012] Another disclosed embodiment relates to a track link. The track
link may include a shoe face and a roller rail opposite the shoe face.
The track link may also include a first end and a second end.
Additionally, the track link may include a first side surface extending
from the first end to the second end between the shoe face and the roller
rail, the first side surface being free of projections. The track link
may also include a second side surface extending from the first end to
the second end between the shoe face and the roller rail opposite the
first side surface, the second side surface being free of projections.

[0013] A further disclosed embodiment relates to an undercarriage
assembly. The under carriage assembly may include a track link having a
first mounting hole with a threaded portion. The assembly may also
include a track shoe having a second mounting hole aligned with the first
mounting hole. Additionally, the undercarriage assembly may include a
bolt extending through the second mounting hole into the threaded portion
of the first mounting hole, the bolt securing the track shoe to the track
link.

[0033]FIG. 4N is a side view of the track link of FIG. 4K from the side
shown in FIG. 4L;

[0034] FIG. 4O is a longitudinal cross-section of the track link of FIG.
4K;

[0035]FIG. 4P is a lateral cross-section of the track link of FIG. 4K
through one mounting hole;

[0036]FIG. 4Q is a lateral cross-section of the track link of FIG. 4K
through another mounting hole;

[0037]FIG. 5A is a perspective view of one track shoe according to the
present disclosure from one side;

[0038] FIG. 5B is a perspective view of the track shoe of FIG. 5A from
another side;

[0039]FIG. 5c is a perspective view of another track shoe according to
the present disclosure from one side;

[0040]FIG. 5D is a perspective view of the track shoe of FIG. 5c from
another side;

[0041]FIG. 6A is a perspective view from one side of a portion of a track
link assembly according to the present disclosure with track shoes
attached;

[0042] FIG. 6B is a perspective view from another side of a portion of a
track link assembly according to the present disclosure with track shoes
attached;

[0043] FIG. 6C is a longitudinal cross-section through an inner track link
of the assembly shown in FIG. 6A;

[0044]FIG. 6D is a longitudinal cross-section through an outer track link
of the assembly shown in FIG. 6A;

[0045]FIG. 7A is a perspective view of one track roller according to the
present disclosure;

[0046]FIG. 7B is a perspective view of another track roller according to
the present disclosure;

[0047] FIG. 7C is a cross-section of the track roller of FIG. 7A through
its rotational axis;

[0048] FIG. 7D is a cross-section of the track roller of FIG. 7B through
its rotational axis;

[0049]FIG. 8A is a first perspective view of track rollers engaging a
track link assembly and shoes according to the present disclosure;

[0050]FIG. 8B is a second perspective view of track rollers engaging a
track link assembly and shoes according to the present disclosure;

[0051] FIG. 8C is an end view of a track roller engaging a track link
assembly and shoes according to the present disclosure;

[0052]FIG. 8D is a side view of track rollers engaging a track link
assembly and shoes according to the present disclosure;

[0053] FIG. 9A is a side view of one embodiment of an idler according to
the present disclosure;

[0054] FIG. 9B is a perspective view of the idler of FIG. 9A;

[0055] FIG. 9C is a cross-section of the idler of FIG. 9A through its
rotational axis;

[0056] FIG. 10A is a perspective view of the idler of FIG. 9A engaging a
track link assembly and shoes according to the present disclosure;

[0057] FIG. 10B is a cross-section of the idler of FIG. 9A engaging a
track link assembly and shoes according to the present disclosure;

[0058] FIG. 10C is cut-away perspective view of the idler of FIG. 9A
engaging a track link assembly and shoes according to the present
disclosure;

[0059] FIG. 11A is a perspective view of another embodiment of an idler
according to the present disclosure;

[0060] FIG. 11B is a side view of the idler of FIG. 11A;

[0061] FIG. 11C is an end view of the idler of FIG. 11A;

[0062] FIG. 11D is a cross-sectional view of the idler of FIG. 11A through
its rotational axis;

[0063] FIG. 11E is a cross-sectional view of the idler of FIG. 11A
engaging a track link assembly and shoes according to the present
disclosure;

[0064] FIG. 12A is a perspective view of a section of another embodiment
of a track link assembly according to the present disclosure;

[0065] FIG. 12B is a perspective view of one track link of the embodiment
of FIG. 12A from one side;

[0066] FIG. 12C is a perspective view of the track link of FIG. 12B from
another side;

[0067]FIG. 12D is a side view of the track link of FIG. 12B from the side
of FIG. 12B;

[0068] FIG. 12E is a side view of the track link of FIG. 12B from the side
of FIG. 12C;

[0069] FIG. 12F is a top view of the track link of FIG. 12B;

[0070] FIG. 12G is a perspective view of another one of the track links of
FIG. 12A from one side;

[0071] FIG. 12H is a perspective view of the track link of FIG. 12G from
another side;

[0072] FIG. 12I is a side view of the track link of FIG. 12G from the side
of FIG. 12G;

[0073]FIG. 12J is a side view of the track link of FIG. 12G from the side
of FIG. 12H;

[0074] FIG. 12K is a top view of the track link of FIG. 12G;

[0075]FIG. 13A is perspective view of carrier skids mounted to an
inclined surface according to one embodiment of the present disclosure;

[0076] FIG. 13B is a side view of the carrier skids of FIG. 13A assembled
in an undercarriage system;

[0077]FIG. 13c is an end view of the carrier skids of FIG. 13A assembled
in an undercarriage system;

[0078] FIG. 14A is a perspective view of another track link according to
the present disclosure; and

[0079] FIG. 14B is a perspective view of yet another track link according
to the present disclosure.

DETAILED DESCRIPTION

[0080]FIG. 2 illustrates a machine 10 with a chassis 12 having an
undercarriage system 14 according to the present disclosure. Machine 10
may be any type of machine that includes a tracked undercarriage system
14. In the example shown in FIG. 2, machine 10 is an excavator having a
superstructure 16 pivotally supported from chassis 12. In this
embodiment, machine 10 may include an implement 18, which may have an
excavating bucket 20 attached to it for digging. Machine 10 may
alternatively be another type of machine, including, but not limited to,
a track-type tractor.

[0081] Undercarriage 14 may be configured to support machine 10 from and
move along the ground, roads, and/or other types of terrain. As best
shown in FIGS. 3A and 3B, undercarriage 14 may include a track roller
frame 22, various guiding components connected to track roller frame 22,
and an endless track 24 engaging the guiding components. In the
embodiment shown in FIGS. 3A and 3B, the guiding components of the
undercarriage 14 include a drive sprocket 26, an idler 28, a roller 30, a
roller 31, a roller 32, a roller 33, a roller 34, a roller 35, a roller
36, track guiding 38, track guiding 40, track guiding 41, track guiding
42, a carrier 44, and a carrier 46.

[0082] Track 24 may include a link assembly 48 that forms a flexible
backbone of track 24, as well as a plurality of shoes 56, 58 secured to
link assembly 48. Link assembly 48 may include a plurality of links 50,
52 connected to one another at pivot joints 54. In FIGS. 3A and 3B, only
half of the links 50, 52 of link assembly 48 can be seen. For each link
50 visible in these figures, link assembly 48 includes a corresponding
laterally spaced link 50. Similarly, for each link 52 visible in these
figures, link assembly 48 includes a corresponding laterally spaced link
52. This pairing of links 50 and links 52 will be explained in greater
detail below. Link assembly 48 may extend in an endless chain around
drive sprocket 26, rollers 30-36, idler 28, and carriers 44, 46. Shoes
56, 58 may be secured to the perimeter of link assembly 48. For example,
track 24 may include one shoe 56 attached to the outside edges of each
laterally spaced pair of links 50, and one shoe 58 attached to the
outside edges of each laterally spaced pair of links 52.

[0083] Rollers 30-36 and track guiding 38, 40 may guide the lower portion
of track 24. Rollers 30-36 may each be suspended beneath track roller
frame 22. For example, each roller 30-36 may be rotationally supported on
an axle 60-66 suspended from track roller frame 22. The undersides of
rollers 30-36 may ride on and guide the links 50, 52 in the lower portion
of the endless chain formed by link assembly 48. Track guiding 38, 40 may
also be suspended from track roller frame 22. Track guiding 38, 40 may
extend adjacent sides of links 50, 52 in the lower portion of the endless
chain formed by link assembly 48, thereby further guiding this portion of
link assembly 48.

[0084] Carriers 44, 46 may guide the upper portion of track 24. To do so,
carriers 44, 46 may extend upward from track roller frame 22 and engage a
portion of link assembly 48 in an upper portion of its endless chain.
Carriers 44, 46 may have various configurations. As shown in FIG. 3A, in
some embodiments, carriers 44, 46 may be skids on which link assembly 48
rides. As discussed in more detail below, in some embodiments carriers
44, 46 may engage bushings 68 of link assembly 48 in a manner such that
carriers 44, 46 help guide link assembly 48. In addition to or instead of
skids, carriers 44, 46 may include rollers on which link assembly 48
rides.

[0085] Drive sprocket 26 and idler 28 may guide the end portions of track
24. Drive sprocket 26 and idler 28 may be suspended from opposite ends of
track roller frame 22. The ends of the endless chain formed by link
assembly 48 may wrap around drive sprocket 26 and idler 28. One or more
portions of drive sprocket 26 may project into spaces between laterally
spaced pairs of links 50 and laterally spaced pairs of links 52. As
described in more detail below, one or more portions of idler 28 may also
project into spaces between laterally spaced pairs of links 50 and
laterally spaced pairs of links 52. Drive sprocket 26 and idler 28 may
rotate about lateral axes to guide the ends of link assembly 48 through
approximately semicircular paths between the lower and upper portions of
the endless chain formed by the link assembly 48. Additionally, because
they extend into spaces between laterally spaced pairs of links 50, 52,
sprocket 26 and idler 28 may guide link assembly 48 in lateral
directions. Sprocket 26 may be rotated by an external power source (not
shown) to move one end of link assembly 48 between the top and bottom
stretches. Driven by sprocket 26, link assembly 48 may, in turn, rotate
idler 28 and rollers 30-36 around their rotation axes. As shown in FIGS.
3A and 3B, drive sprocket 26 may be located adjacent the ground at a
height approximately the same as idler 28. Alternatively, in some
embodiments, drive sprocket 26 may be elevated significantly above the
ground at a height significantly higher than idler 28. For example, drive
sprocket 26 may be positioned above track roller frame 22.

[0088] As FIG. 4A shows, link assembly 48 may include laterally spaced
pairs of links 50 alternating with laterally spaced pairs of links 52.
Links 50 may be positioned laterally between links 52. Thus, the lateral
spacing between each pair of links 52 may be greater than the lateral
spacing between each pair of links 50. Accordingly, links 50 may be
considered inner links, and links 52 may be considered outer links.

[0089] As noted above, links 50, 52 may be connected to one another at
pivot joints 54. The connection at each pivot joint 54 may be
accomplished with a bushing 68 and a pin 70. Each inner link 50 may
include a pair of longitudinally spaced through bores 72. Each through
bore 72 may receive a bushing 68. In some embodiments, one inner link 50
may have its through bores 72 press-fit onto ends of two bushings 68, and
another inner link 50 may have its through bores 72 press-fit onto ends
of the same bushings 68. This may fix the two inner links 50 in laterally
spaced relationship to one another on the bushings 68. To allow a
press-fit between through bores 72 and bushings 68, at least a portion of
the through bores 72 of inner links 50 may have a diameter slightly
smaller than the mating portion of the exterior of the bushing 68. In
some embodiments, the ends of each bushing 68 may protrude slightly from
the through bores 72 of inner links 50. Alternatively, the ends of
bushings 68 may be flush with or recessed inward of the ends of through
bores 72 of inner links 50.

[0090] Each bushing 68 may itself have a through bore 74. One of pins 70
may be installed in the through bore 74 of each bushing 68. Each pin 70
may be longer than each bushing 68, such that ends of each pin 70 may
protrude beyond the ends of the bushing 68 receiving the pin 70. The
through bore 74 of each bushing 68 and each pin 70 may be configured so
that each pin 70 can rotate relatively freely within the through bore 74
of the bushing 68. For example, each pin 70 may have an outer diameter
sufficiently smaller than the inner diameter of through bore 74 to
provide sufficient clearance between the pin 70 and through bore 74 to
allow free rotation.

[0091] Each of outer links 52 may include provisions for registering with
the portions of bushings 68 and pins 70 protruding from inner links 50.
For example, as best shown in FIGS. 4C, 4K, and 4L, each of outer links
52 may include a pair of openings 76. Each opening 76 may include a pin
bore 78 configured to receive an end of a pin 70, as well as a
counterbore 80 configured to register with the end of one of bushings 68.
Each counterbore 80 may be sized to allow clearance between the
counterbore 80 and the end of bushing 68, so that bushing 68 and outer
link 52 may rotate freely relative to one another about the axis of pin
70 and bushing 68. In some embodiments, pin bore 78 may be sized to have
a press fit with the end of pin 70.

[0092] As best shown in FIGS. 4B and 4C, each outer link 52 may have each
of its pin bores 78 press fit onto an end of one of pins 70 with the
associated counterbore 80 facing inward. This may fix the outer links 52
in laterally spaced pairs on the ends of pins 70 with longitudinal ends
of the laterally spaced pairs of inner links 50 connected to and
sandwiched between longitudinal ends of the laterally spaced pairs of
outer links 52. With outer links 52 fixed to pin 70 and inner links 50
fixed to bushing 68, pin 70 may pivot within bushing 68, allowing outer
links 52 and pin 70 to pivot relative to inner links 50 and bushing 68.

[0093] In the assembled state of link assembly 48, each counterbore 80 may
register with the end of one of bushings 68. In embodiments where the
ends of bushings 68 protrude from inner links 50, the end of each bushing
68 may extend partially into the associated counterbore 80.

[0094] Link assembly 48 may also have lubricant, such as oil or grease,
contained in pivot joint 54. For example, lubricant may be contained
within the space between pin 70 and bushing 68. As best shown in FIG. 4C,
to prevent this lubricant from leaking out of pivot joint 54, link
assembly 48 may include a seal 82 in each counterbore 80 of each outer
link 52. As shown in FIG. 4C, seal 82 may be a washer seal that engages
an end face of bushing 68 and an opposing face inside counterbore 80 to
prevent lubricant from escaping pivot joint 54 between these two
surfaces, as well as to prevent debris from entering pivot joint 54
between these two surfaces. Alternatively, seal 82 may have any other
suitable configuration for sealing lubricant in and debris out of pivot
joint 54.

[0095] Inner link 50 may have various configurations. As shown in FIGS.
4D-4J, in some embodiments, inner link 50 may have a monolithic
construction with substantially planar side surfaces 90, 92. Side
surfaces 90, 92 may also be substantially parallel to one another. The
body of inner link 50 may, for example, comprise a flat metal plate with
through bores 72 and a perimeter 94. Thus, the side surfaces 90, 92 of
inner link 50 may omit the protrusions, depressions, and other complex
geometric features on the sides 402 of the links 401 shown in FIG. 1A.
Side surfaces 90, 92 may be monoplanar. Inner link 50 may also omit the
windows 406 and nut seats 408 of the links shown in FIG. 1A. Omitting
windows 406 and 408 may tend to enhance the strength of inner link 50.
However, the configuration of inner link 50 is not limited to the example
shown in the drawings. Some embodiments of inner link 50 may have
windows. Such embodiments may include or omit nut seats.

[0096] Perimeter 94 of inner link 50 may have various shapes. In some
embodiments, perimeter 94 may have a roller rail 96 on its top side and a
shoe face 98 on its bottom side. In some embodiments, the edges of roller
rail 96 may be substantially straight and parallel to one another.
Similarly, the edges of shoe face 98 may be substantially straight and
parallel to one another. In some embodiments, roller rail 96 and shoe
face 98 may be substantially planar. Alternatively, roller rail 96 and/or
shoe face 98 may have other shapes. For example, in some embodiments,
roller rail 96 may arch away from shoe face 98 as it extends toward the
longitudinal center of inner link 50. Additionally, shoe face 98 may
include one or more arches and/or projections. As discussed below, shoe
56 may include reliefs 163 on an inner face 142. Inner link 50 may
include one or more projections on shoe face 98 configured to extend into
reliefs 163 and help hold inner link 50 and shoe 56 in proper relative
positions. In some embodiments, such projections on shoe face 98 may have
substantially the same shape as reliefs 163. Adjacent the longitudinal
ends of roller rail 96, perimeter 94 may curve and/or slope toward shoe
face 98. Similarly, adjacent longitudinal ends of shoe face 98, perimeter
94 may curve and/or slope toward roller rail 96.

[0097] Inner link 50 may include track-shoe-mounting structure configured
to secure a shoe 56 to inner link 50. With no windows or nut seats in
inner link 50, the track-shoe-mounting structure may take various forms.
In some embodiments, the track-shoe-mounting structure may include
mounting holes extending from shoe face 98 into the body of inner link 50
toward roller rail 96. For example, as shown in the cross-sections
illustrated in FIG. 4H-4J, inner link 50 may include a mounting hole 100
and a mounting hole 102. FIG. 4H shows a longitudinal cross-section of
inner link 50 through mounting holes 100, 102. Each of FIGS. 4I and 4J
shows a lateral cross-section of inner link 50 through one of mounting
holes 100, 102, respectively. Mounting hole 100 may have an open end 112
at shoe face 98 and a closed end 114 inside the body of inner link 50.
Similarly, mounting hole 102 may have an open end 116 at shoe face 98 and
a closed end 118 inside the body of inner link 50.

[0098] Mounting holes 100, 102 may include threaded portions 104, 106 and
unthreaded counterbores 108, 110. Counterbores 108, 110 may be disposed
between threaded portions 104, 106 and open ends 112, 116 of mounting
holes 100, 102 at shoe faces 98. As discussed in greater detail below,
the inclusion of counterbores 108, 110 may facilitate achieving
relatively large amounts of bolt stretch in the hardware used to mount
shoe 56 to inner link 50. This may help ensure that shoe 56 remains
securely connected to inner link 50. Threaded portions 104, 106 and
counterbores 108, 110 may have various configurations. Threaded portions
104, 106 may have diameters 120, 122, and counterbores 108, 110 may have
diameters 124, 126. The diameters 124, 126 of counterbores 108, 110 may
be larger than the diameters of threaded portions 104, 106 to allow the
threads of bolts to pass freely through counterbores 108, 110 on the way
to threaded portions 104, 106. Threaded portions 104, 106 may have
lengths 128, 130, and counterbores 108, 110 may have lengths 132, 134.
These lengths 128, 130, 132, 134 will be discussed in greater detail
below.

[0099] Mounting holes 100, 102 may be located in various lateral and
longitudinal positions within link 50. As shown in FIG. 4H, in some
embodiments, mounting holes 100, 102 may be placed equidistant from a
longitudinal center of link 50. As shown in FIGS. 4I and 4J, in some
embodiments, mounting holes 100, 102 may each be centered laterally
between side surfaces 90, 92 of link 50. The lateral and longitudinal
positions of mounting holes 100, 102 are not limited to the examples
provided in the drawings. One or both of mounting holes 100, 102 may be
located at different lateral and/or longitudinal positions than shown in
the drawings.

[0100] The external dimensions of the body of inner link 50 may have
various values based on various considerations. As shown in FIGS. 4F-4J,
inner link 50 may have a length 136, a height 138, and a width 140. The
length 136 may be determined in large part based on a desired distance
between through bores 72 and the amount of material necessary between the
ends and the through bores 72 to provide suitable structural integrity.
Similarly, the height 138 may be determined based in large part on the
size of through bores 72 and the amount of material required above and
below through bores 72 to provide suitable structural integrity and wear
life.

[0101] As best understood by referring to FIGS. 4I and 4J, in some
embodiments, the width 140 of inner link 50 may be determined based in
part on considerations related to the structural integrity of the
portions of inner link 50 between threaded portions 104, 106 of mounting
holes 100, 102 and side surfaces 90, 92. Width 140 of inner link 50 may
have a value that ensures sufficient material to withstand loads applied
to threaded portions 104, 106 by bolts installed therein. For example,
width 140 may have a value of at least about 11/4 times the diameters
120, 122 of threaded portions 104, 106. In some embodiments, width 140
may have a value of at least about 11/2 times the diameters 120, 122 of
threaded portions 104, 106.

[0102] As noted below, in some embodiments, provisions other than threaded
fasteners may be used to mount shoe 56 to inner link 50. For example, in
some embodiments, shoe 56 may be welded to inner link 50. In such
embodiments, inner link 50 may omit mounting holes 100, 102. This may
allow making width 140 of inner link 50 narrower, as inner link 50 would
not need to be wide enough to accommodate mounting holes 100, 102.

[0103] FIGS. 4K-4Q show outer link 52 in detail. Outer link 52 may have a
configuration similar to inner link 50. In some embodiments, outer link
52 may be substantially identical to inner link 50, except openings 76
may differ from through bores 72. In such embodiments, the
above-discussed characteristics of inner link 50 other than openings 72,
including its shape and size and its mounting holes 100, 102, may also be
included in outer link 52.

[0104] As noted above, each opening 76 of outer link 52 may include a pin
bore 78 and a counterbore 80. Each counterbore 80 may have any suitable
dimensions for accommodating seal 82. As shown in FIG. 4C, counterbore 80
may have a length 84, pin bore 78 may have a length 86, and the sum of
length 84 and length 86 may equal a width 140 of outer link 52. Making
counterbore 80 long enough to allow counterbore 80 to fully contain seal
82 and to receive at least a portion of the end of the associated bushing
68 may provide certain advantages. For example, this may create a
labyrinth of surfaces that lubricants and debris must traverse to escape
or enter the interior of pivot joint 54. On the other hand, making
counterbore 80 relatively short may provide a relatively long pin bore
78. This may provide relatively greater friction between pin 70 and pin
bore 78, which may provide a relatively secure engagement between pin 70
and outer link 52. By providing a counterbore 80 with a length 84
slightly greater than the in-use length of seal 82, the embodiment shown
in the figures may achieve both of these advantages. Counterbore 80 may,
for example, have a length 84 of between about 1 and about 5 times the
in-use length of seal 82. Additionally, the length 84 of counterbore 80
may less than about 1/4 of the width 140 of outer link 52. Thus, where
pin bore 78 and counterbore 80 extend across the entire width 140 of
outer link 52, the length 84 of counterbore 80 may be less than about 1/3
of the length 86 of pin bore 78.

[0105] In some embodiments, link assembly 48 may have different provisions
for accommodating seal 82. For example, in some embodiments, link
assembly 48 may house seal 82 at least partially in one or more spaces
within inner link 50. In some such embodiments, each bushing 68 have its
ends recessed inward of the outer end of each through bore 72 of inner
links 50. This may provide space within the end of each through bore 72
adjacent the end of the bushing 68 for seal 82. Each seal 82 may be
housed partially or fully within this space at the end of each through
bore 72. This may allow pin bore 78 to occupy an even greater percentage
of the width 140 of outer link 52, which may further enhance the
engagement between pin 70 and outer link 52.

[0106] Returning to FIG. 4A, the roller rails 96 of inner and outer links
50, 52 may collectively form two roller rails 180 of link assembly 48.
These roller rails 180 may provide a surface on which rollers 30-36 can
ride. Additionally, the edges of roller rails 96 and side surfaces of
inner and outer links 50, 52 may provide lateral guiding surfaces for
rollers 30-36. For example, link assembly 48 may have inner guide
surfaces 182 formed by side surfaces 90 of inner links 50 and the
associated edges of roller rails 96 of inner links 50. Similarly, link
assembly 48 may have outer guide surfaces 184 formed by side surfaces 92
of outer links 52 and associated edges of the roller rails 96 of outer
links 52. Because inner and outer links 50, 52 have planar
configurations, inner and outer guide surfaces 182, 184 of link assembly
48 may not be substantially continuous like the outer guide surfaces 412
of the link assembly 410 shown in FIG. 1A. Rather, inner guide surfaces
182 may be discontinuous, with gaps 186 large enough that inner guiding
features of any given roller 30-36 may not necessarily remain in
engagement with inner guide surfaces 182 at all times. Similarly, outer
guide surfaces 184 may be discontinuous, with gaps 188 large enough that
outer guiding features of any given roller 30-36 may not necessarily
remain in engagement with outer guide surfaces 184 at all times.

[0107] As noted above, the lateral spacing between each pair of outer
links 52 may be greater than the lateral spacing between each pair of
inner links 50. In some embodiments, this may cause one lateral spacing
between the mounting holes 100, 102 in each pair of outer links 52 and a
different lateral spacing between the mounting holes 100, 102 in each
pair of inner links 50. For example, in some embodiments the lateral
spacing between the mounting holes 100, 102 of each pair of outer links
52 may be greater than the lateral spacing between the mounting holes
100, 102 of each pair inner links 50.

[0108] FIGS. 5A and 5B illustrate one of shoes 56 in greater detail, and
FIGS. 5C and 5D illustrate one of shoes 58 in greater detail. As shown in
FIGS. 5A and 5C each shoe 56, 58 may include an inner face 142 for
mounting to links 50, 52, respectively. Each shoe 56, 58 may also include
reliefs 163 on its inner face 142. In some embodiments, reliefs 163 may
be grooves or slots that extend laterally across inner face 142. As shown
in FIGS. 5B and 5D, each shoe 56, 58 may also have an outer face 144 for
engaging the ground. Each shoe 56, 58 may include two laterally spaced
pairs of mounting holes 146, 148. The longitudinal spacing between each
mounting hole 146 and the paired mounting hole 148 may equal the spacing
between mounting holes 100, 102 of inner and outer links 50, 52.
Additionally, each shoe 56 may have its pairs of mounting holes 146, 148
laterally spaced from each other substantially the same distance as the
lateral spacing between each pair of inner links 50 in link assembly 48.
On the other hand, each shoe 58 may have its pairs of mounting holes 146,
148 laterally spaced from one another substantially the same distance as
the lateral spacing between each pair of outer links 52 in link assembly
48. Thus, the lateral spacing between mounting holes 146, 148 of shoe 56
may differ from the lateral spacing between mounting holes 146, 148 of
shoe 58.

[0109] This arrangement of mounting holes 146, 148 of shoes 56, 58 may
allow mounting holes 146, 148 to register with mounting holes 100, 102 of
links 50, 52, so that bolts may be secured through mounting holes 146,
148 into mounting holes 100, 102 to retain shoes 56, 58 to link assembly
48. FIGS. 6A-6D illustrate shoes 56, 58 secured to link assembly 48. Each
shoe 56 may have its inner face 142 placed against the shoe faces 98 of a
laterally spaced pair of inner links 50 with each pair of mounting holes
146, 148 of the shoe 56 registering with the mounting holes 100, 102 of
one of the inner links 50. Similarly, each shoe 58 may have its inner
face 142 placed against the shoe faces 98 of a laterally spaced pair of
outer links 52 with each pair of mounting holes 146, 148 of the shoe 58
registering with the mounting holes 100, 102 of one of the outer links
52.

[0110] Each shoe 56, 58 may also include trap holes 147, 149 extending
between inner face 142 and outer face 144. Trap holes 147, 149 may
provide an escape path for material like dirt or gravel that has worked
its way into link assembly 48. In some embodiments, one or both of shoes
56, 58 may omit one or both of trap holes 147, 149. Alternatively, one or
both of shoes 56, 58 may include more than two trap holes 147, 149.

[0111] Shoes 56, 58 may also include notches in their edges to provide
escape paths for material like dirt and gravel. For example, shoe 56 may
have notches 151, 153. Notches 151, 153 may be spaced from one another by
a distance approximately equal to the lateral spacing between outer links
52 in link assembly 48. Thus, notches 151, 153 may be spaced from one
another by a different amount than mounting holes 146, 148 of shoe 56.
Shoe 58 may have notches 159, 161 on its edge. Notches 159, 161 may be
spaced from one another by a different amount than notches 151, 153 of
shoe 58. For example, notches 159, 161 may be laterally spaced from one
another by a distance substantially equal to the lateral spacing between
inner links 50 of link assembly 48. Thus, the lateral spacing between
notches 159, 161 may be different from the lateral spacing between
mounting holes 146, 148 of shoe 58.

[0112] As shown in FIGS. 6B-6D, bolts 150 may be secured through each of
mounting holes 146, 148 into mounting holes 100, 102 of links 50, 52 to
secure shoes 56, 58 to link assembly 48. Bolts 150 may be secured into
mounting holes 100, 102 by engaging threads of bolts 150 to threaded
portions 104, 106 of each of mounting holes 100, 102. As best shown in
FIGS. 6B-6D, the portions of bolts 150 extending through counterbores
108, 110 of mounting holes 100, 102 and through mounting holes 146, 148
of shoes 56, 58 may be free to stretch as bolts 150 are tightened.
Because counterbores 108, 110 and mounting holes 146, 148 allow a
significant portion of each bolt 150 to stretch, it may be possible to
provide a relatively large amount of stretch in each of bolts 150 without
unduly stressing the bolts 150. To help achieve this bolt stretch,
counterbores 108, 110 may have significant lengths 132, 134. For example,
each counterbore 108, 110 may have a length 132, 134 of at least about
1/2 of its diameter 124, 126, in some embodiments, each counterbore 108,
110 may have a length 132, 134 of at least about 3/4 of its diameter 124,
126. Similarly, each counterbore 108, 110 may have a length 132, 134 of
at least about 1/2 or in some embodiments at least about 3/4, of the
diameter 120, 122 of the associated threaded portion 104, 106.

[0113] FIGS. 7A-7D illustrate rollers 34 and 35 in greater detail. In some
embodiments, each of rollers 30-33 may have substantially the same
configuration as roller 34, and roller 36 may have substantially the same
configuration as roller 35. Rollers 34 and 35 may each include a central
passage 152 through which the associated axle 64, 65 extends. Each roller
34, 35 may include two roller treads 154, 156 for engaging the roller
rails 180 of link assembly 48. Each roller tread 154, 156 may be, for
example, a substantially cylindrical surface extending partway along the
axis of each roller 34, 35. The roller treads 154, 156 of each roller 34,
35 may be disposed on axially opposite sides of a center plane of the
roller 34, 35. As shown in FIGS. 7B and 7D, roller tread 154 may have a
width 155, and roller tread 156 may have a width 157. The widths 155, 157
of roller treads 154, 156 may be the same or different. In some
embodiments, the width 155, 157 of each roller tread 154, 156 may be at
least twice the width 140 of each of inner and outer links 50, 52.
Similarly, roller treads 154, 156 may have the same diameter or different
diameters.

[0114] Each roller 34, 35 may also have provisions for providing lateral
guidance between rollers 34, 35 and track 24. For example, axially
outward of roller treads 154, 156 each of rollers 34, 35 may include a
pair of outer guide flanges 158, 160 extending radially outward of roller
treads 154, 156, respectively. As shown in FIGS. 7C and 7D, outer guide
flange 158 may have a height 162 from roller tread 154. Outer guide
flange 160 may have a height 164 from roller tread 156. The heights 162,
164 of guide flanges 158, 160 may be the same or different. The width
(e.g., axial distance) between outer guide flanges 158, 160 may be
slightly greater than the width between outer surfaces 92 of outer links
52 in link assembly 48. This may allow outer links 52 of link assembly 48
to fit between outer guide flanges 158, 160.

[0115] In addition to outer guide flanges 158, 160, roller 34 may have a
single center guide flange 166 disposed between roller treads 154, 156.
Center guide flange 166 may extend from one roller tread 154 to the other
roller tread 156. In some embodiments, radially outer portions of the
lateral edges of center flange 166 may have rounded corners 168, 170.
Between corners 168, 170, center guide flange 166 may have a
substantially cylindrical surface 172 of substantially constant diameter.
Substantially cylindrical surface 172 may include one or more openings.
For example, as shown in FIG. 7A, substantially cylindrical surface 172
may include an opening 174 for supplying lubricant into central passage
152 of roller 30.

[0116] Center guide flange 166 may have a height 178 relative to adjacent
roller treads 154, 156. Height 178 may have various values. In some
embodiments, the height 178 of center guide flange 166 may be at least
about 10% of the widths 155, 157 of each of roller treads 154, 156.
Center guide flange 166 may have a greater height in some embodiments.
For example, the height 178 of center guide flange 166 may be at least
about 15% of the widths of 155, 157 of each of roller treads 154, 156.
Additionally, in some embodiments, the height 178 of center guide flange
166 may be at least about 1/2 of the heights 162, 164 of outer guide
flanges 158, 160. Configuring center guide flange 166 with such
substantial height may help ensure that center guide flange 166 remains
in proper guiding arrangement with track 24 as vertical and/or angular
movement of one or more shoes 56, 58 occurs.

[0117] In contrast to roller 34, roller 35 may lack central guide flange
166. In lieu of central guide flange 166, roller 35 may include a central
groove 176. Roller 35 may include central groove 176 in order to allow
the central portion of roller 35 to clear components that connect idler
28 to track roller frame 22. As noted above, roller 36 may be configured
substantially the same as roller 35. Accordingly, roller 36 may similarly
include a central groove 176.

[0118] Each of rollers 30-36 may be constructed from a single, unitary
piece of parent material without welds or other joining techniques. For
example, each of rollers 30-36 may be formed from a piece of bar stock
cut, machined, and/or otherwise shaped to include the features discussed
above. Structures formed from a single, unitary piece of parent material
may include, for example, structures that are formed without welded
joints, glued joints, fastened joints, press-fit joints, or the like to
hold different portions of the structure together.

[0119] Rollers 30-36 are not limited to the configurations shown in the
drawings. For example, each roller 30-34 may have multiple central guide
flanges in lieu of a single central guide flange 166. Alternatively, in
some embodiments, rollers 30-36 may all be configured without any central
guide flange. Similarly, a subset or all of rollers 30-36 may omit outer
guide flange 158 and/or outer guide flange 160.

[0120] FIGS. 8A-8D illustrate in detail how rollers 30-36 may engage link
assembly 48. Each of FIGS. 8A-8D shows only a subset of rollers 30-36,
but the illustrations of how roller 34 engages link assembly 48 also
demonstrate how rollers 30-33 engage link assembly 48, and the
illustrations of how roller 35 engages link assembly also demonstrate how
roller 36 engages link assembly 48. As shown in the figures, the roller
treads 154, 156 of each roller 30-36 may ride on the roller rails 180 of
link assembly 48.

[0121] The outer and center guide flanges 158, 160, 166 of rollers 30-34
may guide rollers 30-34 relative to link assembly 48. As best shown in
FIG. 8C, when roller treads 154, 156 are riding on roller rails 180 of
link assembly 48, outer guide flanges 158, 160 may extend down outside of
outer guide surfaces 184 of link assembly 48 formed by outer surfaces 92
of outer links 52. At the same time, center guide flange 166 may extend
down between inner guide surfaces 182 of link assembly 48 formed by inner
surfaces 90 of inner links 50. As noted above and shown in FIGS. 8A and
8B, inner and outer guide surfaces 182, 184 may be discontinuous, having
gaps 186, 188. As shown in FIG. 8D, the gaps 188 in outer guide surfaces
184 may be longer than a chord length 190 of outer guiding flanges 158,
160. The chord length 190 may be the length of a chord across each outer
guiding flange 158, 160 coincident with roller rail 180. With gaps 188
having a length greater than the chord length 190 of the outer guiding
flanges 158, 160 of rollers 30-34, outer guiding surfaces 184 may not
guide outer guiding flanges 158, 160 of a roller 30-34 when the roller
30-34 is disposed in the middle of one of gaps 188. Similarly, gaps 186
of inner guiding surfaces 182 may have lengths greater than a chord
length (not shown) of center guiding flange 166, such that inner guiding
surfaces 182 may not guide center guiding flange 166 when a roller 30-34
is disposed in the middle of one of gaps 186.

[0122] However, including both outer guiding flanges 158, 160 and center
guiding flange 166 on rollers 30-34 may ensure proper guiding of rollers
30-34 on link assembly 48 at all times. When one of rollers 30-34 is
riding on a pair of outer links 52 in the middle of one of gaps 186 of
inner guiding surfaces 182, outer guide flanges 158, 160 may cooperate
with the outer surfaces 92 of those outer links 52 to restrain lateral
movement between the roller 30-34 and link assembly 48. On the other
hand, when one of rollers 30-34 is riding on inner links 50 in the middle
of one of gaps 188 in outer guiding surfaces 184, center guide flange 166
may cooperate with inner surfaces 90 of inner links 50 to restrain
lateral movement between the roller 30-34 and link assembly 48. When one
of rollers 30-34 is riding on ends of both inner links 50 and outer links
52, outer guiding flanges 158, 160 may cooperate with outer surfaces 92
of outer links 52 to provide guiding, while center guiding flange 166
cooperates with inner surfaces 90 of inner links 50 to provide
simultaneous guiding.

[0124] FIGS. 9A-9C show one embodiment of idler 28 in greater detail.
Idler 28 may include a hub 192 and a body 194. Hub 192 may be configured
to be connected to track roller frame 22 in such a manner that idler 192
may rotate about a rotational axis 196 relative to track roller frame 22.
Body 194 of idler 28 may be fixedly engaged to hub 192.

[0125] As best shown in FIG. 9C, in some embodiments, hub 192 may be
constructed of a single, unitary piece of parent material. For example,
in some embodiments, hub 192 may be machined from a single piece of
metal, forged in one piece, or cast in one piece. Alternatively, hub 192
may be formed from multiple pieces joined together by welding, fastening,
press-fitting, and/or other means.

[0126] In some embodiments, body 194 of idler 28 may be a solid disk.
Thus, as shown in FIG. 9C, which is a cross-section of idler 28 through
its rotation axis 196, body 194 may have no internal cavities like the
internal cavity 420 of the idler 414 shown in FIG. 1C. Body 194 may also
have substantially planar sides 198. As they extend radially outward,
sides 198 may follow substantially straight lines without curves or
angles. Additionally, sides 198 may be substantially parallel to one
another. At its radially outer perimeter, body 194 may have a center
tread surface 200. In contrast to the idler 414 shown FIGS. 1B and 1C,
idler 28 may omit tread shoulders 428. In some embodiments, center tread
surface 200 may include a substantially cylindrical surface substantially
concentric with rotational axis 196. In some such embodiments, the
substantially cylindrical portion of center tread 200 may extend from the
outer radial portion of one side 198 to the outer radial portion of the
other side. In such embodiments, center tread portion 200 may be flat and
straight across the full width of body 194. In other embodiments, some
portions of center tread portion 200 may curve and/or slope as they
extend in the direction of the width of body 194. For example, center
tread portion 200 may include radiuses and/or bevels (not shown) adjacent
sides 198.

[0127] In some embodiments, body 194 of idler 28 may be locally hardened.
For example, the radially outer portion of body 194, including center
tread 200, may be hardened, while portions radially inward may not be
hardened. Local hardening may be achieved by any suitable method,
including, but not limited to, induction hardening, flame hardening,
hardfacing and/or cladding. Alternatively, body 194 may be uniformly
hardened or not hardened at all.

[0128] Various approaches may be employed to attach hub 192 and body 194
of idler 28 to one another. In some embodiments, hub 192 may include an
outwardly facing mounting face 202, and body 194 may include an inwardly
facing mounting face 204 configured to mate with mounting face 202. For
example, mounting face 202 may be an outwardly facing cylindrical surface
on hub 192, and mounting face 204 may include an inwardly facing
cylindrical surface of substantially the same size on body 194. An
inwardly facing cylindrical mounting face 204 may be formed, for example,
by forming a circular opening in the center of the disk forming body 194.
In some embodiments, mounting face 202 of hub 192 may be formed on the
radially outer portion of a rib 206 of hub 192. Sides of rib 206 may
include concave radiused surfaces, which may limit stress concentrations
in these regions. Body 194 may be positioned on hub 192 with mounting
face 204 surrounding mounting face 202, and body 194 may be secured in
this position using various approaches. In some embodiments, idler 28 may
have welds 208 connecting body 194 to hub 192. In combination with or in
lieu of welds 208, press-fitting and/or staking may be used to secure
body 194 to hub 192.

[0129] FIGS. 10A-10C provide greater detail regarding the manner in which
idler 28 may engage track 24. As shown in FIG. 10A, an end portion of
link assembly 48 of track 24 may wrap around idler 28. As shown in FIGS.
10B and 10C, radially outer portions of body 194 of idler 28 may extend
into the spaces between laterally spaced pairs of inner links 50 and
outer links 52. This may create some limits on lateral movement between
link assembly 48 and idler 28, thereby helping to guide link assembly 48
laterally. Center tread 200 of idler 28 may abut the bushings 68 at the
pivot joints 54 of link assembly 48. At the lower side of idler 28,
center tread 200 may ride atop one or more of bushings 68, as shown in
FIGS. 10B and 10C. At the upper side of idler 28, one or more of bushings
68 may ride atop center tread 200. Abutting center tread 200 against
bushings 68 may place body 194 deep within the space between links 50, 52
of link assembly 48, which may help ensure that proper guiding engagement
is maintained between idler 28 and link assembly 48

[0130] As best shown in FIG. 10B, the disk forming body 194 of idler 28
may have a width 207, and link assembly 48 may have a gap width 209. Gap
width 209 may be a lateral distance between the laterally innermost
portions of links 50, 52. In the case of the embodiment shown in FIG.
10B, this may be the lateral distance between inner side surfaces 90 of
inner links 50. Width 207 of body 194 and gap width 209 may have various
values. In some embodiments, width 207 may be at least about 50% of gap
width 209. Configuring disk body 194 of idler 28 with a width of at least
about this magnitude may help ensure sufficient contact area between
center tread surface 200 and bushings 68 to keep stresses at this
interface desirably low. Additionally, configuring disk body 194 of idler
28 with a width of at least about 50% of the gap width 209 may help
ensure effective lateral guiding between idler 28 and link assembly 48.
On the other hand, in some embodiments, width 207 of disk body 194 may
have a value of less than about 90% of gap width 209. This may help
ensure sufficient clearance between idler 28 and links 50, 52 of link
assembly 48 to allow material like dirt and or gravel to escape from this
space.

[0131] FIGS. 11A-11E illustrate another embodiment of an idler 210. Idler
210 may include a hub 212 and a body 214. Hub 212 may be configured to be
connected to track roller frame 22 in a manner such that idler 210 may
rotate around a rotation axis 213. Body 214 may be fixedly engaged to hub
212.

[0132] Hub 212 may have various configurations. As best shown in FIG. 11D,
in some embodiments, hub 212 may have a first side 212A and a second side
212B secured to one another. Sides 212A, 212B may be secured to one
another using means including, but not limited to, welding, fastening,
and/or press-fitting. Alternatively, in some embodiments, hub 212 may be
constructed from a single, unitary piece of parent material.

[0133] Body 214 may include two disks 216 laterally spaced relative to one
another. Between disks 216, idler 210 may include a gap 226. Each disk
216 may have an inner side surface 218 and an outer side surface 220. In
some embodiments, inner and outer side surfaces 218, 220 of each disk 216
may be substantially planar and substantially parallel to one another.
Additionally, disks 216 may be substantially parallel to one another with
inner and outer side surfaces 218, 220 of one disk 216 substantially
parallel to inner and outer side surfaces 218, 220 of the other disk 216.
Outer side surfaces 220 of disks 216 may form the outer side surfaces of
idler 210. Outer side surfaces 220 of disks 216 may be spaced from one
another by a distance less than the distance between inner side surfaces
90 of inner links 50 in link assembly 48, so that idler body 214 may fit
between inner links 50.

[0135] Idler body 214 may also include a plurality of reinforcing spacers
228 extending laterally between disks 216 radially outward of hub 212. In
some embodiments, reinforcing spacers 228 may be circumferentially spaced
from one another. For example, reinforcing spacers 228 may be placed at
equal angular intervals around rotation axis 213 of idler 210.
Reinforcing spacers 228 may have various configurations. In some
embodiments, reinforcing spacers 228 may be bars extending substantially
parallel to rotation axis 213 of idler 210. Reinforcing spacers 228 may
be round bars with substantially circular cross-sections. Alternatively,
reinforcing spacers 228 may be bars with other cross-sectional shapes,
including, but not limited to, square, hexagonal, or octagonal. In other
embodiments, one or more of reinforcing spacers 228 may have shapes other
than bars. For example, in some embodiments, one or more of reinforcing
spacers 228 may be plates that extend laterally between disks 216 and
radially outward relative to rotation axis 213.

[0136] Various approaches may be implemented to engage reinforcing spacers
228 between disks 216. As shown in FIG. 11D, in some embodiments, each
reinforcing spacer 228 may include a center section 230 and two end
sections 232 with smaller cross-sections than the center section 230.
Where the center section 230 and end sections 232 meet, each reinforcing
spacer 228 may include shoulders 234. Where reinforcing spacers 228 are
round bars with substantially circular cross-sections, center section 230
may have a substantially circular cross-section with one diameter, and
each end section 232 may have a substantially circular cross-section with
a smaller diameter. Each disk 216 may have provisions for mating with end
sections 232. For example, disks 216 may include openings 236 that are
each configured to receive an end section 232 of one of reinforcing
spacers 228. Each opening 236 may have a cross-section large enough to
receive an end section 232 but too small to receive center section 230.
As shown in FIG. 11D, each reinforcing spacer 228 may have each of its
end sections 232 installed in an opening 236 of one of disks 216 with the
shoulders 234 of the reinforcing spacer 228 abutted against inner side
surfaces 218 of disks 216.

[0137] Various means may be used to secure each reinforcing spacer 228 in
these positions, in some embodiments, reinforcing spacers 228 may be
welded to each disk 216. For example, each end section 232 of a
reinforcing spacers 228 may be welded to one of disks 216 at the
interface between the end section 232 and the surrounding opening 236.
Other securing means may be used in combination with or instead of
welding. For example, end sections 232 may be press fit into openings
236.

[0138] Various approaches may be used to secure body 214 to hub 212. In
some embodiments, hub 212 may include outwardly facing mounting faces
238, and body 214 may include inwardly facing mounting faces 240
configured to mate with mounting faces 238. Mounting faces 240 of body
214 may include, for example, inwardly facing surfaces of central
openings in disks 216. In some embodiments, mounting faces 240 may each
include an inwardly facing substantially cylindrical surface. In such
embodiments, mounting faces 238 may include outwardly facing
substantially cylindrical surfaces configured to fit inside of and mate
with the inwardly facing substantially cylindrical surfaces of mounting
faces 240. Adjacent each mounting face 238, hub 212 may have a laterally
outwardly facing shoulder 239. Body 214 may be positioned on hub 212 with
inwardly facing mounting surfaces 240 surrounding outwardly facing
mounting faces 238 of hub 212 and inner side surfaces 218 of disks 216
abutting shoulders 239. Various means may be used to secure body 214 in
this position. In some embodiments, body 214 may be welded to hub 212 at
the interface between each inwardly facing mounting face 240 and each
outwardly facing mounting face 238. Additionally, or alternatively, body
214 may be press-fit and/or staked to hub 212.

[0139] The configuration of the mounting structures for securing body 214
to hub 212 is not limited to the example shown in FIG. 11D. In some
embodiments, these mounting structures may have features for suppressing
stress concentrations adjacent the interface between body 214 and hub
212. For example, similar to the idler 28 shown in FIGS. 9A-9C, idler 210
may have outwardly facing mounting faces 238 formed on one or more ribs
with concave radiused side surfaces.

[0140] Idler 210 may engage link assembly 48 in much the same way that
idler 28 does. For example, an end portion of link assembly 48 may wrap
around idler 210. Additionally, as FIG. 11E shows, outer radial portions
of body 214 of idler 210 may extend into spaces between inner and outer
links 50, 52 of the portion of link assembly 48 wrapped around idler 210.
Thus, radially outer portions of side surfaces 220 of disks 216 may be
disposed between inner side surfaces 90, 92 of links 50, 52. The split
center tread surface 222 formed by the radially outermost portions of
disks 216 may abut bushings 68 between links 50, 52.

[0141] FIG. 12A illustrates another embodiment of a link assembly 244
constructed with a different configuation of track links 242A, 242B.
FIGS. 12B-12K illustrate track links 242A, 242B in greater detail. Link
242A may have ends 246A, 248A, a shoe face 250A on its bottom side, a
roller rail 252A on its top side, and side surfaces 254A, 256A. As best
shown in FIGS. 12D and 12E, ends 246A, 248A, shoe face 250A, and roller
rail 252A may collectively form a perimeter 282A of link 242A. Link 242B
may have ends 246B, 248B, a shoe face 250B on its bottom side, a roller
rail 252B on its top side, and side surfaces 254B, 256B. As best shown in
FIGS. 12I and 12J, ends 246B, 248B, shoe face 250B, and roller rail 252B
may collectively form a perimeter 282B of link 242B. In some embodiments,
perimeters 282A, 282B of links 242A, 242B may be substantially identical.

[0142] In some embodiments, links 242A, 242B may have a nonplanar
configuration. As viewed from above, link 242A may offset to the right as
it extends from end 246A to end 248A. Between end 248A and end 246A, link
242A may have one or more portions that angle and/or curve to the right.
For example, a center section 258A of link 242A may angle and/or curve to
the right as it extends away from end 246A toward end 248A. On the other
hand, link 242B may have its end 248B offset to the left relative to its
end 246B, with a center section 258B that angles and/or curves to the
left as it extends away from end 246B toward end 248B. Thus, the portions
of side surfaces 254A, 256A, 254B, 256B adjacent ends 246A, 246B may be
laterally offset relative to the portions of side surfaces 254A, 256A,
254B, 256B adjacent ends 248A, 248B. And portions of sides surfaces 254A,
256A, 254B, 256B between ends 246A, 246B and ends 248A, 248B, such as
portions in the middle of links 242A, 242B, may curve and/or angle
laterally.

[0143] Side surfaces 254A, 256A, 254B, 256B may be free of protrusions. In
some embodiments, side surfaces 254A and 256A of link 242A may extend
substantially parallel to one another. Similarly, side surfaces 254B and
256B of link 242B may extend substantially parallel to one another. Link
242A may have a substantially constant thickness (i.e., the distance
between its side surfaces 246A and 248A) between its ends 246A and 248A.
Similarly, link 242B may have a substantially constant thickness (i.e.,
the distance between its side surfaces 246B and 248B) between its ends
246B and 248B. Additionally, in some embodiments, at each point between
ends 246A, 248A, each of sides surfaces 254A, 256A may extend straight
vertically. Similarly, at each point between ends 246B, 248B, each of
sides surfaces 254B, 256B may extend straight vertically.

[0144] Links 242A, 242B may be constructed with various amounts of offset.
In some embodiments, the lateral offset between the ends 246A, 248A of
link 242A may be substantially the same as the thickness between its
sides 254A, 256A. Additionally, the portion of side surface 256A at end
246A may be substantially coplanar with the portion of side surface 254A
at end 248A. Similarly, the lateral offset between the ends 246B, 248B of
link 242B may be substantially the same as the thickness between its
sides 254B, 256B, and the portion of side surface 256B at end 246B may be
substantially coplanar with the portion of side surface 254B at end 248B.

[0145] As best shown in FIGS. 12C and 12H, links 242A, 242B may include
openings 260A, 260B adjacent their ends 246A, 246B. Opening 260A may
extend through link 242A between its side surfaces 254A, 256A. Similarly,
opening 260B may extend through link 242B between its side surfaces 254B,
256B. Each of openings 260A may be configured to receive the bushing 68
discussed above. For example, each of openings 260A may be configured to
have a press-fit with bushing 68.

[0146] Links 242A, 242B may also include openings 262A, 262B adjacent
their ends 248A, 248B. Opening 262A may extend through link 242A between
its side surfaces 254A, 256A. Opening 262A may include a pin bore 264A
and a counterbore 266A. Counterbore 266A may extend from side surface
254A into link 242A. Pin bore 264A may extend from the inner portion of
counterbore 266A to side surface 256A. Similarly, opening 262B may
include a counterbore 266B extending from side surface 254B into link
242B, as well as a pin bore 264B extending from the inner portion of
counterbore 266B to side surface 256B.

[0147] Each pin bore 264A, 264B and counterbore 266A, 266B may have
various configurations. In some embodiments, each pin bore 264A, 264B may
be configured to receive an end of one of the pins 70 discussed above.
For example, in some embodiments, each pin bore 264A, 264B may be
configured to have a press-fit with one end of one of pins 70. Each
counterbore 266A, 266B may have a cross-section larger than the
cross-section of the associated pin bore 264A, 264B. In some embodiments,
each counterbore 266A, 266B may have a cross-section larger than end
portions of bushing 68. This may enable each counterbore 266A, 266B to
receive an end portion of a hushing 68 while allowing relatively free
rotation between the bushing 68 and the counterbore 266A, 266B.

[0148] Each counterbore 266A, 266B may also be configured to partially or
fully contain one of the seals 82 in the manner discussed above in
connection with FIG. 4C. Each counterbore 266A, 266B may, for example,
have a length of between about 1 and about 5 times the in-use length of
seal 82. Additionally, the length of each counterbore 266A, 266B may be
less than about 1/4 of the thickness of the link 242A, 242B. Thus, the
length of each counterbore 266A, 266B may be less than about 1/3 of the
length of the associated pin bore 264A, 264B.

[0149] In addition to openings 260A, 260B, 262A, 262B, links 242A, 242B
may include other openings. For example, link 242A may include windows
268A, 270A extending from side surface 254A to side surface 256A.
Similarly, link 242B may include windows 268B, 270B extending from side
surface 254B to side surface 256B.

[0151] The shoe-mounting structure of links 242A, 242B is not limited to
the configurations shown in FIGS. 12B-12K. In some embodiments, for
example, links 242A, 242B may have blind, threaded mounting holes (like
mounting holes 100, 102 discussed above) extending up from shoe faces
250A, 250B. In such embodiments, the mounting holes may include threaded
portions and unthreaded counterbores with the same dimensions and
configurations discussed above in connection with links 50, 52.
Alternatively, the shoe-mounting structure of links 242A, 242B may
include features for riveting, welding, or otherwise securing track
shoes.

[0152] As shown in FIG. 12A, in link assembly 244, each link 242A may be
paired with and laterally spaced from a link 242B. Each pair of links
242A, 242B may have side surfaces 254A, 254B facing each other, such that
links 242A, 242B splay laterally outward from one another as they extend
from their ends 246A, 246B to their ends 248A, 248B. This may allow the
ends 246A, 246B of one pair of links 242A, 242B to fit between the ends
248A, 2.48B of another pair of links 242A, 242B with openings 260A, 260B
of one pair of links 242A, 242B substantially aligned with openings 262A,
262B of the other pair of links 242A, 242B.

[0153] Each pair of links 242A, 242B may be pivotally connected to the
adjacent pair of links 242A, 242B at a pivot joint 280. Openings 260A,
260B of one pair of links 242A, 242B may be secured around a bushing 68.
For example, in some embodiments, openings 260A, 260B of a first pair of
links 242A, 242B may be press-fit around end portions of bushing 68,
which may hold the first pair of links 242A, 242B in laterally spaced
relationship and prevent rotation between the first pair of links 242A,
242B and the bushing 68. A pin 70 may be installed inside the through
bore 74 of bushing 68 with ends of the pin 70 protruding out of each end
of the bushing 68. A second pair of laterally spaced links 242A, 242B may
have its openings 262A, 262B secured around the ends of pin 70, such as
by press-fitting. This may fix the second pair of links 242A, 242B in
laterally spaced relation with its link ends 248A, 248B disposed outward
of the link ends 246A, 246B of the first pair of links 242A, 242B. With
the second pair of links 242A, 242B fixed to pin 70 and the first pair of
links 68 fixed to bushing 68, pin 70 may rotate within bushing 68,
allowing the second pair of links 242A, 242B and pin 70 to pivot relative
to the first pair of links 242A, 242B and bushing 68.

[0154] FIGS. 13A-13C show carriers 44, 46 in greater detail. In the
embodiment shown in the drawings, carriers 44, 46 are carrier skids. FIG.
13A shows carrier skids 44, 46 and a portion of track roller frame 22
separate from the rest of undercarriage system 14. FIG. 13B is a close up
side view of carrier skids 44, 46 assembled in undercarriage system 14.
FIG. 13c is a close up end view of carrier skids 44, 46 assembled in
undercarriage system 14. Carrier skid 44 may include a first vertically
extending leg 290A, a second vertically extending leg 292A, and a bridge
294A connecting first and second vertically extending legs 290A, 292A. In
some embodiments, first vertically extending leg 290A, second vertically
extending leg 292A, and bridge 294A may be constructed from a piece of
plate material. An upper side of bridge 294A may include a first carrier
surface 296A. Carrier surface 296A may include a first ramp 298A that
slopes upward as it extends away from first vertically extending leg 290A
toward second vertically extending leg 292A. Carrier surface 296A may
also include a second ramp 300A that slopes upward as it extends away
from the second vertically extending leg 292A toward the first vertically
extending leg 290A. In some embodiments, carrier surface 296A may include
a crown 302A disposed between ramps 298A, 300A.

[0155] Carrier skid 46 may include a first vertically extending leg 290B,
a second vertically extending leg 292B, and a bridge 294B connecting
first and second vertically extending legs 290B, 292B. In some
embodiments, first vertically extending leg 290B, second vertically
extending leg 292B, and bridge 294B may be constructed from a piece of
plate material. An upper side of bridge 294B may include a first carrier
surface 296B. Carrier surface 296B may include a first ramp 298B that
slopes upward as it extends away from first vertically extending leg 290B
toward second vertically extending leg 292B. Carrier surface 296B may
also include a second ramp 300B that slopes upward as it extends away
from the second vertically extending leg 292B toward the first vertically
extending leg 290B. In some embodiments, carrier surface 296B may include
a crown 302B disposed between ramps 298B, 300B.

[0156] As best shown in FIG. 13c, carrier skid 44 may include a laterally
inner side surface 304A and a laterally outer side surface 306A. Carrier
skid 46 may include a laterally inner side surface 304B and a laterally
outer side surface 306B. Laterally inner side surface 304A may extend
substantially parallel to laterally outer side surface 306A. In some
embodiments, laterally inner side surface 304A and laterally outer side
surface 306A may be substantially planar. In some embodiments, laterally
inner and outer side surfaces 304B, 306B of carrier skid 46 may also be
substantially planar and parallel to one another. Additionally, side
surfaces 304A, 306A of carrier skid 44 may be substantially parallel to
side surfaces 304B, 306B of carrier skid 46.

[0157] Carrier skids 44, 46 may be mounted to an inclined surface 308 of
track roller frame 22 with the vertically extending legs 290A, 292A,
290B, 292B extending upward. Carrier skids 44, 46 may be secured to
surface 308 by various means, including, but not limited to, welds and/or
fasteners. Inclined surface 308 may slope in a lateral direction. Carrier
skids 44, 46 may be laterally spaced from one another. Carrier skid 44
may extend upward from a point 310A on inclined surface 308. Carrier skid
46 may extend vertically upward from a point 310B on inclined surface
308. Points 310A, 310B may be laterally spaced from one another.
Accordingly, the height of surface 308 at point 310A may differ from the
height of surface 308 at point 310B. Specifically, the height of surface
308 at point 310A may be lower than the height of surface 308 at point
310B. Carrier skid 44 may be taller than carrier skid 46. In other words,
the vertical distance between the portion of carrier skid 44 engaged to
inclined surface 308 and the top of carrier surface 296A may be greater
than the vertical distance between the portion of carrier skid 46 engaged
to inclined surface 308 and the top of carrier surface 296B. In some
embodiments, carrier skid 44 may be taller than carrier skid 46 by an
amount substantially equal to the difference between the height of
surface 308 at points 310A and 310B of inclined surface 308. This may
place carrier surfaces 296A, 296B at substantially the same height.

[0158] As best shown in FIG. 13c, carrier skids 44, 46 may extend
vertically upward into spaces between the laterally spaced pairs of inner
and outer links 50, 52 of link assembly 48. Carrier surfaces 296A, 296B
may engage the undersides of bushings 68 of link assembly 48. Carrier
surfaces 296A, 296B may be laterally spaced from one another, such that
carrier surfaces 296A, 296B engage different lateral portions of bushings
68. This may help reduce wear on bushings 68 by ensuring that a given
lateral portion of each bushing 68 slides along only one of carrier skids
44, 46 during each revolution of track 24. Laterally inner side surfaces
304A, 304B of carrier skids 44, 46 may face toward one another, and
laterally outer side surfaces 306A, 306B of carrier skids 44, 46 may face
away from one another. In some embodiments, laterally outer side surfaces
306A, 306B may be disposed adjacent inner side surfaces 90 of inner and
outer links 50, 52. This may help guide link assembly 48 in lateral
directions.

[0159] FIGS. 14A and 14B illustrate alternative configurations of the
above-described links. In particular, FIG. 14A illustrates link 50',
which is an alternative configuration of link 50, and FIG. 14B
illustrates link 242A', which is an alternative configuration of link
242A. Link 50' differs from link 50 in that it includes side surfaces
90', 92' having protrusions 500. Link 242A' differs from link 242A in
that it includes side surfaces 254A', 256A' having protrusions 550 and
600, and in that it includes mounting holes 272A', 274A', which are
substantially identical to mounting holes 100, 102, instead of mounting
holes 272A and 274A and windows 268A, 270A. Although links 50' and 242A'
are compared to links 50 and 242A, respectively, it should be understood
that the features of links 50' and 242A' (e.g., protrusions 500, 550, and
600) could be included in any of the above-described links.

[0160] As shown in FIG. 14A, protrusions 500 may extend vertically along
surfaces 90', 92' and adjacent to mounting holes 100', 102'. Protrusions
500 may provide certain advantages. For example, they may ensure that
link 50' contains sufficient material to withstand loads applied to
threaded portions of mounting holes 100', 102' by bolts installed
therein. In doing so, protrusions 500 may render the above-discussed
relationships between width 140 of link 50 and the diameters of threaded
portions 104, 106 inapplicable to link 50', allowing a width 140' of link
50' to be smaller than width 140 and minimizing the total amount of
material contained by link 50'.

[0161] Referring to FIG. 14B, while protrusions 550 may be substantially
identical to protrusions 500 (i.e., they may extend vertically along
surfaces 254A', 256A' and adjacent to mounting holes 272A', 274A', and
may provide similar advantages), protrusion 600 may instead surround pin
bore 264A'. In doing so, protrusion 600 may extend pin bore 264A' such
that it is longer than pin bore 264A of link 242A, allowing for a
stronger press-fit connection between pin bore 264A' and a pin installed
therein.

[0162] The components of undercarriage system 14 may be constructed of
various materials. In some embodiments, rollers 30-36, inner links 50,
outer links 52, shoes 56, shoes 58, bushings 68, pins 70, hub 192 of
idler 28, and body 194 of idler 28 may be constructed of metal. For
example, each of these components may be constructed of a ferrous metal,
such as steel or iron.

[0163] The configuration of undercarriage system 14 is not limited to the
configurations discussed above and shown in the drawings. For example,
different approaches may be used to secure various of the components to
one another. In lieu of having a press fit to hold outer links 52 and/or
links 242A, 242B to pins 70, other approaches may be used, including, but
not limited to, welding each pin 70 to outer links 52. Similarly, instead
of having shoes 56, 58 secured to inner and outer links 50, 52 with bolts
150, shoes 56, 58 may be secured to inner and outer links 50, 52 by other
means, including, but not limited to welding and/or riveting. In
embodiments where shoes 56, 58 are welded to inner and outer links 50,
52, shoes 56, 58 may omit mounting holes 146, 148. Likewise, means other
than those discussed above and shown in the drawings may be used to
secure various of the other components of undercarriage system 14 to one
another. Additionally, the various components of undercarriage system 14
may have different shapes and/or sizes than those discussed above and
shown in the drawings. Furthermore, undercarriage system 14 may have
different numbers of its various components than shown in the drawings.
For example, undercarriage system 14 may include different numbers of
rollers 30-36, links 50, 52, and/or shoes 56, 58 than shown in the
drawings.

[0164] Additionally, undercarriage system 14 may use known configurations
of certain components in combination with components of the configuration
shown in the drawings. For example, undercarriage system 14 may use a
known configuration of an idler with the configuration of link assembly
48 and rollers 30-36 shown in the drawings. In some such configurations,
the idler used may have tread surfaces that ride on links 50, 52, rather
than bushings 68. Similarly, undercarriage system 14 may use a known
configuration of a link assembly with one of the idlers 28, 210 shown in
the drawings. The disclosed components and known configurations of
components may be used in any suitable combination within undercarriage
system 14.

INDUSTRIAL APPLICABILITY

[0165] The disclosed embodiments may have use in any application where it
may be beneficial to provide a mobile machine with a tracked
undercarriage. The configurations of the disclosed embodiments may
provide a number of benefits. Among the advantages of the disclosed
embodiments, the configurations of many of the components lend themselves
to cost-effective manufacturing methods. Additionally, the disclosed
embodiments may have greater strength and better performance than known
configurations. Thus, the disclosed embodiments may provide for a lower
cost, higher performance undercarriage.

[0166] The configurations of inner and outer links 50, 52 may lend
themselves to low cost manufacturing. An inner link 50 or an outer link
52 with parallel, substantially planar sides may be manufactured from a
plate of material having a thickness substantially the same as the
desired width 140 of the inner link 50 or outer link 52. Various methods
may be employed to make from such plate material a blank having a
perimeter approximating or matching the desired perimeter 94 of the
finished inner link 50 or outer link 52. For example, laser cutting could
be used to separate the blank from the plate material by cutting the
plate material along a path approximating or matching the desired
perimeter of the finished links 50, 52. The processes used to separate
the blank from the plate material could also be used to rough in or
finish other features. For example, in connection with a process of laser
cutting a blank from the plate material, openings corresponding to
through bores 72 (for inner link 50) or openings 76 (for outer link 52)
could be laser-cut into the blank. Alternatively, the entire process of
forming through bores 72 or openings 76 may be performed after completion
of the blank.

[0167] In some instances, various finishing processes may be performed on
the blank to produce a finished inner link 50 or outer link 52. For
example, machining operations may be performed to refine the perimeter
94, to refine the through bores 72 or features of the openings 76 (e.g.,
pin bores 78 and counterbores 80), and/or to create other features, such
as mounting holes 100, 102. Additionally, various other finishing
processes, including, but not limited to, heat treating and painting, may
be performed to produce the final inner link 50 or outer link 52. Thus,
the disclosed configurations of inner links 50 and outer links 52 may
reduce or eliminate the need for expensive manufacturing processes like
forging.

[0168] Similar processes may be used to manufacture the embodiment of
links 242A, 242B shown in FIGS. 12A-12K. In some embodiments, the process
of making one of links 242A, 242B may begin by cutting a link blank from
plate material, such as by cutting the plate material along a path
matching or approximating the perimeter 282A, 282B of the link 242A,
242B. This may be done, for example, by laser cutting. Openings 260A,
260B, 262A, 262B, windows 268A, 268B, 270A, 270B, mounting holes 272A,
274A, 272B, 274B, and nut seats 276A, 278A, 276B, 278B may be formed
using various processes, including, but not limited to laser cutting
and/or machining operations. The offset in each link 242A, 242B may be
created at any point in the process by bending the workpiece. As with
links 50, 52, various finishing processes may be performed to create the
finished links 242A, 242B. These finishing operations may include, but
are not limited to, machining, heat treating, and painting.

[0169] Links 50' and 242A' may be manufactured using processes similar to
those used to manufacture links 50 and 242A. Before and/or after
machining mounting holes 100', 102', 272A', 274A', however, and while
links 50' and 242A' are warm, links 50' and 242A' could be pierced to
extrude protrusions 500 and 550. Additionally, a clamp fixture could be
used to force protrusion 600 and pin bore 264A' out from surface 256A'.

[0170] The disclosed configurations of rollers 30-36 may similarly reduce
or eliminate the need for certain expensive manufacturing processes. In
some embodiments, each roller 30-36 may be manufactured from round bar
stock with a diameter that approximates or matches the largest diameter
part or parts (e.g. outer guide flanges 158, 160) of the finished roller
30-36. From this bar stock, a roller blank may be generated by cutting
off a piece of the bar stock with a length approximating or equaling the
overall width of the finished roller 30-36. In some embodiments, the
roller blank may then be transformed into a finished roller 30-36 by
machining the various features of the roller 30-36. For example, the
central passage 152 may be machined through the center of the blank. To
form the outer features, such as roller treads 154, 156 and center guide
flange 166 or center groove 176, machining operations may be performed to
remove material from the outer surface of the roller blank. For instance,
these features may be machined into the roller 30-36 by turning the
roller blank in a lathe. Subsequently, various other finishing operations
may be performed on the roller 30-36, including, but not limited to heat
treating and painting operations. Thus, the need for certain expensive
manufacturing processes like forging and/or welding may be reduced or
eliminated. Manufacturing each roller 30-36 from a single, unitary piece
of parent material may also give the roller good strength and durability
by avoiding joints that may be subject to fatigue failures.

[0171] The configuration of idler 28 may also lend itself to
cost-effective manufacturing processes and may give idler 28 good
strength and durability. For example, construction of hub 192 from a
single, unitary piece of parent material may contribute to achieving
these benefits. Similar to rollers 30-36, hub 192 may be manufactured
from round bar stock with a diameter that approximates or matches the
largest diameter part or parts (e.g. mounting face 202) of the finished
hub 192. From this bar stock, a hub blank may be generated by cutting off
a piece of the bar stock with a length approximating or equaling the
overall width of the finished hub 192. In some embodiments, various
features of the hub 192 may be machined. For example, material may be
removed from radially outer portions of the blank to form rib 206. As
with producing the other components, producing hub 192 may also involve
various finishing processes, including, but not limited to, machining,
heat treating, and painting.

[0172] Additionally, in embodiments where body 194 of idler 28 includes a
solid disk with substantially flat, planar sides, the solid disk may be
readily formed from plate metal. To form the flat disk from plate metal,
various technologies may be employed to separate from the plate metal a
disk that approximates or matches the desired final shape of the disk. In
some embodiments, laser cutting may be used to form a disk blank by
cutting one circle in the plate for the center opening of the disk and
cutting a larger circle in the plate to simultaneously form an outer
perimeter of the disk and separate the disk blank from the rest of the
plate. Subsequently, various finishing processes may be performed on the
blank to form a finished disk. For example, in some embodiments where the
disk will be welded to hub 192 of idler 194, machining operations may be
used to refine and/or shape mounting face 204 of the disk. Similarly,
various processes may be used to refine the shape of other parts of the
disk, such as the mounting face 202. Additionally, other finishing
processes may be performed on the disk, including, but not limited to
heat treating and painting. Thus, the disclosed configurations of idler
28 may also reduce or eliminate the need for expensive manufacturing
processes like forging and welding.

[0173] Idler 210 may also lend itself to cost-effective manufacturing
methods. Disks 216 of idler 210 may be readily formed from plate
material. For example, a blank for each disk 216 may be formed by cutting
one circle in the plate for the center opening of the disk 216 and
cutting a larger concentric circle to separate the disk from the plate.
Subsequently, various finishing operations like those discussed above may
be executed to form a finished disk 216. The openings 236 in each disk
216 may be formed using cutting and/or machining processes. Similarly,
the reinforcing spacers 228 of idler 210 may be formed using cutting
and/or machining processes. In the case of the embodiment shown in FIGS.
11A-11E, for example, making each reinforcing spacer 228 may involve
making spacer blanks by cutting a length of bar stock having a
cross-section matching or approximating the desired final cross-section
of the center section 230 of the reinforcing spacer 228. Machining
processes may be used to give end sections 232 smaller cross-sections
than center section 230. Cutting processes may be performed by laser
cutting or by other cutting methods.

[0174] Like many of the other components of undercarriage system 14,
carrier skids 44, 46 may be manufactured from plate material. A blank may
be formed by cutting the plate material along a path matching or
approximating the outer perimeter of the vertically extending legs 290,
292 and the bridge 294. As with the other components, various finishing
operations may be performed to produce the finished carrier skids 44, 46.
These finishing operations may include, but are not limited to,
machining, heat treating, and painting.

[0175] The use of carrier skids 44, 46 in lieu of carrier rollers may also
help reduce the cost of undercarriage system 14. Carrier skids 44, 46 may
be significantly less expensive to produce than carrier rollers.
Additionally, using carrier skids 44, 46 instead of carrier rollers may
eliminate the need to include bearings and/or other expensive components
for rotationally supporting carrier rollers.

[0176] Methods of manufacturing the disclosed embodiments are not limited
to those discussed above. While the disclosed embodiments may reduce the
need for forging and welding operations, these processes may be used to
make the disclosed parts. Additionally, processes other than those
explicitly discussed may be used in the manufacture of the disclosed
components.

[0177] It will be apparent to those skilled in the art that various
modifications and variations can be made in the disclosed systems without
departing from the scope of the disclosure. Other embodiments of the
disclosed systems will be apparent to those skilled in the art from
consideration of the specification and practice of the systems disclosed
herein. It is intended that the specification and examples be considered
as exemplary only, with a true scope of the disclosure being indicated by
the following claims and their equivalents.

Patent applications by Gregory J. Kaufmann, Metamora, IL US

Patent applications by Mark S. Diekevers, Metamora, IL US

Patent applications by Robert L. Meyer, Metamora, IL US

Patent applications by Timothy A. Thorson, Morton, IL US

Patent applications in all subclasses With detachable grouser for endless chain track